Carburetors for internal combustion engines



A. WEILAND July 21, 1959' CARBURETORS FOR INTERNAL COMBUSTION ENGINES Filed March 4, 1958 3 Sheets-Sheet 2 //V -I/////!/! N O M H 8 2 u -m n m n 1 e a M m w y Ill C FIG. 3

INVENTOR ATTORNEY FIG 6 July 21, 1959 A. W EILAND 2,895,723

v CARBURETORS FOR INTERNAL COMBUSTION ENGINES Filed March 4, 1958 v 3 Sheets-Sheet 3 lgaj'gal-Inllmm T g 22 I8 W INVENTOR 9 ALFRED WE ILAND ATTORNEY United States Patent CARBURETORS FOR INTERNAL COMBUSTION ENGINES Alfred Welland, Clearwater, Fla. Application March 4, 1958, Serial No. 719,153

19 Claims. Cl. 261-44) The present invention relates to fuel control for internal combustion engines and more particularly to an improved carburetor for motor vehicles. The outstanding existing problem in carburetors on motor car engines and other variable speed engines is to reduce exhaust hydrocarbons during deceleration by precise controlof fuel under all operating conditions and to stop excessive flow of fuel when the throttle is closed on deceleration. In attempts to remedy this inefficiency, carburetors have been tried with multi barrels having an assortment of jets, needle valves, supplemental pumps, venturis and the like without solving the problem. With such jets located between the throttle and the air intake solid fuel continues to flow or spill from the jets causing rich mixtures and excessive hydro-carbons when the throttle is opened. The sudden closing of the throttle produces a high vacuum between the throttle and the engine valves causing excessive flow of fuel from many types of slow speed jets now used between the throttle and the engine valves. When travelling behind cars, this is readily observed in the form of black smoke when cars decelerate to normal speeds. The damaging eliect of excess wet gasoline on the cylinder walls is well known. .Devices have been introduced to reduce the high vacuum on sudden closing of the throttle, all of which introduce a related braking problem on deceleration and when operating in low gear when the engine is used as a brake.

An object of the invention is to provide a carburetor wherein the inefliciency and disadvantages of present day carburetors are overcome.

Another object of the invention is to provide a carburetor wherein variationsuof vacuum in the motor manifold are compensated by a responsive proportioning of the fuel mixture.

A further object is to provide a carburetor wherein means operate to produce an effective lean fuel mixture with no excess fuel loss to the higher vacuum produced by deceleration of the motor speed, whereby fuel waste and wet cylinder walls are prevented.

Generally, therefore, the carburetor of the invention comprises a down draft air intake barrel wherein the fuel discharge forms a part of the throttle such fuel being fed from a supplemental offset cylinder having a reciprocable air lift-piston controlled by the operation of the throttle tometer the fuel proportionately to the variations of vacuum in the motor manifold. In addition the reciprocable air lift piston with its fuel metering pin is located at or near the float level when the throttle is almost closed reducing the head or pressure under which fuel flows into the well, at the same time reducing thequantity of fuel flowing past thefuel metering pin. The reciprocable air lift piston is also valuable in priming the engine and providing additional fuel for cold starting.

- In the accompanying drawings:

Fig. 1 is a sectional elevation view of a carburetor embodying one form of the invention;

2 Fig. 2 is a side elevation view of the carburetor looking towards the air lift unit;

Fig. 3 is a section view on line 3-3 of Fig. 1; Fig. 4 is a fragmentary section view on line 44 of Fig. 1 showing the throttle valve closed;

Fig. 5 is alike section view showing the throttle valve in full open position;

Fig. 6 is a partial section view on line 6-6 of Fig. 1 showing a detail of the air lift air discharge ports;

Fig. 7 is a section view on line 7--7 of Fig. 8;

Fig. 8 is a top plan view of a modified form of th invention;

Fig. 9 is a section view on line 9-9 of Fig. 8;

Fig. 10 is a section view on line 1010 of Fig. 9; and

Fig. 11 is an elevation view of the linkage side of the modified construction. 7

Referring to the drawings, the tubular air intake barrel 10 of the carburetor communicates at one end with the atmosphere and at the other end to the manifold of the motor to which the carburetor is attached.

For controlling the flow of air, a throttle valve 11 is mounted on a shaft 12 which extends transversely of the barrel 10 to project at opposite ends to be supported respectively by bearings 13. The throttle valve is formed with two oppositely disposed wings 14 and 15 which together have a length to close the barrel passage when turned to closing position. The valve 11 is fixed to the shaft 12, in this instance, by a set screw 17 and has a length to span the transverse width of the barrel 10, as shown in Fig. 1. Also the valve 11 has a centrally located radial port 18, while the wing 15 has a through passage 20 to terminate against the inner wall of the barrel 1 10 for cutting off fuel discharge in throttle closed position.

In order to discharge fuel into the barrel 10 when the throttle valve is open, or partly open, the shaft 12 is tubular to form an axial conduit 21 with which two radial ports 22 and 23 communicate. The port 22 is located to register with the port 18 of the valve 11 and the port 23 is located to register with the passage 20 and consequently fuel drawn through the conduit 21 has two ports discharging by way of the throttle valve into the barrel 10 on the manifold'end thereof.

For supplying fuel to the conduit 21 one projecting end of the shaft 12 mounts a tubular member 24 internally mounting a fixed cylinder 25 having a side discharge port 26 in register with the conduit 21 and communicating 'with a fuel supply well 27, the lower end of which is closed by an apertured plug 28. The aperture in the plug 28 forms a fuel inlet but serves also as a guide for a metering pin 30 having a relatively short lengthwise flat 31 at an angle to the axis of the pin to form a channel increasing in depth as the pin is moved downwardly through the plug 28. A chamber 32 is attached to the bottom of the cylinder 25 and has an inlet 33 for fuel which is supplied from a conventional float reservoir or other means as the source of fuel. A strainer 34 is mounted'within the chamber 32 to encircle the metering pin aperture for the usual purpose.

In order to set and adjust the pin 30 it is attached to and depends from a metering air lift piston 35 mounted for reciprocating movement in the cylinder 25 but with its upper end projecting therefrom for attachment to a novel control to be later described. One side. of the piston 35 is formed with a longitudinally disposed slot 36 which is closed at its upper end but open at its lower end to communicate with fuel supply well 27.

' This slot 36 opens into the discharge port 26 and is long 38 communicating with the upper end of an axial bore 40 through which the pin 30 passes with an encircling .clearance.

For introducing the supplemental air, or air lift air, into the bore 40 by wayof the slot 37, the outer end of the cylinder supporting member 24 has an annular flange 41 which forms a cup communicating by a port 42, in its base, with a port 43 in the wall of the cylinder 25. This port 43 opens into the slot 37 whereby entering supplemental air reaches the bore 40 as metered by the registering position of the port 38. The opening formed by the flange 41 is closed by a screen 44 as a strainer for entering air. The member 24 clamps the cylinder 25 as a fixed part of the barrel by suitable studs 44'. A guide stud 45 traverses the bases of the cup and the wall of the cylinder 25 to enter the slot 37 to prevent relative turning of the piston 25 while allowing metering axial travel thereof.

In order to control the discharge of the air lift air from the bore 40 this latter is closed at its lower end by an attached apertured bushing 46 which is also attached to the metering pin 30. The body of the bushing 46 projects below the bottom of the bushing to terminate in an air deflector flange 47 spaced from the bushing end and having a diameter greater than the transverse spacing of the bushing apertures. In the present instance the bushing has illustratively four such through parts 48 to discharge air axially to be deflected radially outward along the deflector to pick up fuel in the well 27 to be discharged as a fuel mist. The number of parts 48 in the bushing body may be varied to meet different conditions and the invention is not to be limited to an exact number. As will be explained the lower, or deflector carrying end of the air lift piston 35 is arranged to locate its deflector at a predetermined submerged level in the well 27, preferably for example, about three-eighths of an inch when no air is entering, such submergence varying in response to variations in manifold vacuum as motor speed varies. In this connection it should be noted that the fuel flows into the well 27 by gravity under a fixed head determined by a float chamber to provide a fixed level below the horizontal plane passing through the axis of the throttle shaft.

In this form of the invention the submergence setting and its variation by vacuum changes is accomplished in part by a coil spring 50 compressed between the deflector flange 47 and the plug 28 to maintain a static upward pressure to lift the piston 25. Such pressure is in opposition to a piston setting pressure applied by a flexible cam spring strip 51 hearing against a roller 52 suitably journalled in the projecting end of the piston 35. The strip 51 is mounted by a plurality of adjusting screws 53 in spaced relation to the inner face of an arcuate flange 54 which forms a lateral extension of a crank 55. The ends of the strip 51 are respectively anchored in posts 56 while the camming contour of the strip 51 is obtained by the screws 53 in order to follow the swing of the flange 54 and maintain the required variable hold down pressure on the piston 25 in response to throttle changes. One of the screws 53 is positioned in axial alinement with the piston 35 to give positive straight line pressure in opposition to the pressure of the coil spring 50. The initial setting of the alined screw 53 is such as to produce a balance between the two opposed pressures and leave the deflector flange submerged at the depth corresponding to substantially the closed position of the throttle valve.

As a means for simultaneously actuating the throttle and shifting the piston 25 to change the submerged setting of the deflector in accordance with the variations of vacuum, the crank 55 is keyed to a projecting end of the throttle shaft 12 and is arranged to be operated by any suitable linkage attached to a coupling knob 56 which projects laterally from the crank 55. This linkage 4 is that actuated by the accelerating pedal of the motor, as will be understood.

With respect to the setting and balancing of the piston 25 it should be noted that the flexible strip 51 diverges from the face of the flange 54 at both sides of the axial line of the piston in order to maintain spring contact with the roller at all times. In this way a non-effective tangent spring movement is prevented. An important feature of the air lift piston control resides in having the axis of the cylinder 25 offset from the axis of the air intake barrel and consequently there is a more rapid movement of the air lift piston during the time when the crank 55 is passing top center to quickly respond to vacuum changes.

A further novel feature of the invention serves to remedy the general fault of carburetors wherein excess fuel continues to flow from the jets upon sudden closing of the throttle and collects in the air and gas passages ,so' that sudden opening of the throttle discharges this excess as 'a too rich mixture and hydrocarbons. The remedy provided by applicant includes maintaining a high velocity of air through the air passages of the air lift and means to reduce the quantity of liquid fuel at the same time raising the air lift piston to reduce the depth to which it is submerged in the fuel, and the pressure or head under which the fuel flows into the well. The excess fuel below the deflector on the air lift piston is stored and used on the next acceleration of speed or power. In other words, there is only one source of fuel, always under high velocity and control. In operation the cam strip 51 is adjusted by the axially disposed screw 53 to move the piston 35 against'the pressure of the compression coil spring until the two pressures are balanced and locate the flange deflector 47 submerged in the fuel in the well by approximately /8". This fuel level is determined by the supply from the float chamber and is preferably about /8" below the horizontal plane passing through the axis of the throttle valve, namely the axis of the conduit 21. The setting of the piston adjustment also positioned the metering pin 30 for proper restricted passage of fuel. During the foregoing setting the throttle is in closed position. With the opening of the throttle to start the motor, the crank 55 swings both the throttle and the strip 51 and consequently the camming action depresses the air lift piston 35 to draw supplemental air into the well through the ports 42 and 43 while also lowering the metering pin 30 to give the desired proportioned mixture. Thus with the initial starting high vacuum the needed rich mixture is drawn into the motor manifold. As the throttle opens for normal running the offset relation of the air lift piston gives an accelerated movement to the piston 35 which, with its related cam, maintains the metering pin 30 and air lift control in step so that the fuel mixture remains substantially constant at any fixed throttle opening thereby giving a lean mixture for light loads and the proper mixture for greater loads at lower engine speeds. During sudden deceleration the passages for the air from the air lift well compensate for the increased vacuum by restricting the fuel flow so that excess fuel does not accumulate.

In the modified form of the invention shown in Figs. 7 to 11 the air intake barrel 60 is formed with an integral laterally disposed annular extension 61 in which the cylinder 62 of the air lift unit is fixedly supported in a position with its axis offset from the axis of the barrel 60. As in the previously described form the lower end of the cylinder 62 is closed by a cap 63 which is apertured for the passage of the metering pin 64 having its proporting tapered flat 65 as heretofore explained. The fuel receiving chamber member 66 with strainer is carried by the cylinder 62 and has the fuel inlet 67. The upper end of the cylinder 62 is formed with two oppositely disposed air inlet openings which are covered respectively by screens 68. These openings admit air into the tubular air lift piston 71 by way of the juxtaposed slots 72 at the upper end of the piston. This entering air is drawn axially of the piston and discharges laterally by the deflector flange 73 across the fuel in the well 74 to carry a premixture of air and fuel through outlet port 75 into the bore 76 of the throttle valve shaft 77 by the variations of vacuum. The lower end portion of the piston 71 is of reduced diameter to provide a clearance 78 communicatingwith the port 75. The apertured closure unit for the lower end of the piston 71 is of like construction to that described for Fig. 1 and is identified by like reference numerals to avoid repetition since its function here has not been changed. b V

For raising and lowering the piston 71 and metering pin 64 in response to vacuum changes, a ball joint plug 80 closes the upper end of the piston 71 to which it is attached as a lift part. The metering pin 64 is threaded into the plug 80 to be suspended thereby and follow its adjusting movements. The co'acting, or thrust ball 81, of the joint is one end of camming screw 82 threaded through a bearing pin 83 traversing the bifurcated end of a yoke 84 which is keyed to a shaft 85 passing through the barrel 60 where its projecting end is keyed to its operating crank 86. Thus while the control yoke 84 can be swung about with the shaft 85 as a center, the offset pin 83 carries the ball joint screw 82 in a different are to produce either a lowering or a raising of the piston 71 according to the direction of movement of the yoke.

As in the preferred form of the invention the control for the proportioning of the supplemental mixture by reciprocation of the piston is arranged to be actuated synchronously with the throttle opening and closing. Accordingly the crank 86 is connected by a link 87 to the crank 88 which is keyed to the throttle valve shaft 77. As shown the accelerator pedal of the vehicle is connected by an actuating rod 90 to the linkage for dual swinging of both cranks 86 and 88.

In this modified form of the invention the throttle valve, its mounting and control ports are the same as like parts shown in Figs. 1 and 4, therefor the same numerals are similarly applied. However the conduit 21 in the shaft 77 is a continuation of the bore 76 which communicates by way of the port 75 with the bore of the cylinder 62. Thus the description and showing of the throttle valve assembly apply as well to Figs. 9 and of the modification.

In operation the common linkage, for the throttle valve and air lift control, simultaneously actuates these parts so that variations of barrel vacuum likewise vary the proportioning of the fuel mixture from the single fuel supply. By reason of the offset axis of the air lift cylinder with respect to the axis of the intake barrel 60, the air lift piston 71 is given an accelerated movement as the crank 87 passes top center to transmit a corresponding leverage movement to the air lift piston control screw 82.

In this form of the invention the setting of the air lift piston 71 is by adjusting the screw 82 which is initially screwed in for a selected downward positioning of the piston and the needle valve fuel control with respect to the fuel level. As in the other form the piston deflector is substantially submerged in the fuel well.

Recapitulating the operation and control has as one important novel feature the use of one fuel supply through an air lift well with a reciprocable air lift. The combination of reciprocable air lift piston and metering pin is adjusted to provide the proper mixture for average loads and speeds at any one throttle setting, which mixture becomes lean as the load is reduced and engine speed increases; and provides the means to eliminate excessive fuel and hydro-carbons on sudden deceleration of the motor. The most important, novel and new feature in this design is the use of one fuel supply through an air lift well with a reciprocable air lift piston and metering pin, with the resulting change in the head or pressure on the flow of liquid fuel into the fuel well. In other words, the metering pin reduces the flow of liquid fuel but the air lift piston only picks up the fuel above the deflecto 'which due to the reduced distance the air lift piston" 1s submerged, also reduces the flow of fuel due to the reduced head between the float level and the deflector on the air lift piston. This design allows for larger fuel passages in the metering pin, as in this case, with the stances.

In almost closed throttle position, the head or pressure on the flow of fuel from the float chamber can be A" or and full open throttle could be 1" or more.

In any position of the throttle, the position of the air lift piston and its metering pin are adjustable by the cam face to provide the most economical mixture, as the load is reduced at that throttle setting, the speed of the engine increases, the flow of fuel does not increase, producing a lean mixture. If the load increases at the same throttle setting, the engine speed decreases and the mixture becomes richer causing a very economical operation.

Another important new feature is the throttle valve with a fixed opening for. slow speed and idling of the engine, and the passage #20 which is closed on idling or deceleration. The outlet area of this passage #20 increases as the throttle is opened. The total area of the two outlets in the throttle are substantially equal to the area of the air intake in the air lift piston.

It will now be apparent that a complete unitary carburetor assembly has been devised wherein the quantity of fuel is precisley controlled regardless of vacuum changes due to acceleration and decelerating motor speeds and is therefore substantially constant under all normal speeds of the vehicle. Furthermore when decelerating the larger air passages as compared to the throttle discharge ports result in a leaving of the discharged main mixture so that no'excess fuel can accumulate as Waste and undesirable hydrocarbon.

Having now described my invention I claim:

1; A carburetor comprising an air intake barrel, a throttle valve in said barrel, a cylinder offset from said barrel having a fuel outlet to said barrel and a supplemental inlet, a fuel well in said cylinder, a reciprocable air 11ft piston in said cylinder having a passage to deliver supplemental air from said inlet through said well to said mounts said throttle having a conduit to receive mixture from said outlet and discharge it through said throttle ports. I 4. A carburetor comprising a barrel as a main air intake, a throttle valve operatively mounted in said barrel, a vertically disposed cylinder forming a fuel supply well at its lower end, means forming a conduit to deliver fuel from said well into said barrel, said cylinder having an inlet above said well for supplemental air reciprocable air lift piston in said cylinder having parts to be submerged in the fuel in said well and also forming a passage from said supplemental air inlet to said parts, means forming a conduit from said well to deliver the mixture of fuel and supplemental air to said barrel, and common mechanical means for operating said throttle and air lift piston, whereby said supplemental air and fuel mixture is proportioned according to the position of said throttle.

5. A carburetor according to claim 4, wherein means operates to proportion the movement of said piston with respect to the movement of said throttle.

6. A carburetor according to claim 5 wherein said proportioning means is a cam actuated by said operating means to move said piston in one direction, and an opposing spring to move said piston in the opposite direction.

7. A carburetor comprising a barrel as a main air intake, throttle valve operatively mounted in said barrel, said valve having a fuel conduit and a port to discharge into said barrel, a cylinder attached to said barrel in axial offset relation and forming a well for fuel and a supplemental air inlet above the fuel level, an air lift piston reciprocably mounted in said cylinder having an axial bore open at one end to communicate with said air inlet and forming a clearance with the wall of said cylinder for passage of air to said conduit, said clearance having a,

greater area than the throttle conduit and port as a reserve for excess fuel, and common means for operating said throttle and piston.

8. A carburetor according to claim 7, wherein the lower end of said piston is submerged a predetermined depth in the fuel in the well, and a plug is located in said bore having air holes to discharge into said well.

9. A carburetor according to claim 8, wherein the bore plug has a flange across and spaced from the plug holes to deflect discharged air radially outward.

10. A carburetor according to claim 9 wherein means including a needle valve controls fuel to said well, said needle valve being attached to and depending from said piston.

11. A carburetor comprising a barrel as a main air intake, a throttle valve operatively mounted in said barrel, a fuel well having a predetermined fuel level therein, a needle valve for controlling the supply of fuel to said well, a cylinder attached to said barrel with its axis offset to the barrel axis, said cylinder having air intake for supplemental air above the fuel level in said well a conduit for delivering fuel air from said cylinder into said barrel, an air lift piston for actuating said needle valve, said piston forming a passage for the supplemental air from said intake, means including a crank for operating said throttle and piston in unison to vary the supply of fuel and supplemental air according to changing throttle conditions.

12. A carburetor according to claim 11 wherein said crank means includes a flexible settable cam across the top of said piston, and spring means maintaining said piston in riding contact with said cam. i

13. A carburetor according to claim 11 wherein said crank means includes a ball joint connection to reciprd cate said piston according to throttle valve positions.

14. A carburetor according to claim 13 wherein means is operable to adjust the joint connection to set said piston for a predetermined submergence in the fuel in said well. a

15. A carburetor comprising an air intake barrel, a throttle valve including an attached shaft having an axial conduit closed at one end and two fuel discharge ports from said conduit, said valve having a passage forming a. communication between one shaft port and said barrel in open position of said valve, and a port in register with the other of said shaft ports, means journalling said shaft transverselyof said barrel, a cylinder having a fuel outlet to said shaft conduit and an inlet for supplemental air,

a fuel well in said cylinder under fuel level float control,

a reciprocable air lift piston in said cylinder for drawing air through said inlet, means operated by said piston for controlling the fuel level, crank means for operating said throttle valve shaft, and means following the movement of said crank means for proportioning the air lift piston air and fuel control in a ratio predetermined by vacuum variations in said barrel.

.from said inlet to said parts, means including a metering pin depending from said piston to control the fluid entering said well, and common mechanical means for shifting said piston and throttle valve for varying the submergence of said supplemental air inlet and fuel air mist discharge ports in the fuel in said well.

18. A carburetor according to claim 17 wherein said throttle valve has a permanent discharge port for slow speed operation and a spherical surface abutting the wall of the intake barrel to vary the fuel mist discharge according to the position of said throttle.

19. A carburetor comprising a barrel having a main air inlet and a fuel mixture outlet, a tubular shaft transverse of said barrel and closed at one end, a throttle valve carried by said shaft having a discharge port close to the axis of said barrel and a second port abutting the bore of said barrel, said ports communicating with the interior of said shaft, a cylinder mounted on said barrel forming a fuel well said cylinder having a supplemental air inlet and a fuel mixture outlet to said shaft, an air lift piston in said cylinder forming passages respectively for directing supplemental air from said inlet through said fuel well and for directing the supplemental air and fuel from the well to said outlet, means to throttle the flow of air and fuel from said shaft, a metering pin on said air lift piston, and mechanical means to increase and decrease the depth to which said piston is submerged in the fuel well.

References Cited in the file of this patent UNITED STATES PATENTS 1,383,044 Weiland June 28, 1921 2,190,314 Firth Feb. 13, 1940 2,223,987 Firth Dec. 3, 1940 

